must_future

BoxFutures cannot be marked #[must_use] because they are just type definitions. This newtype struct wraps a BoxFuture with something that can be marked #[must_use].

Will Not Compile:

#![deny(unused_must_use)]

use futures::future::FutureExt;

#[tokio::main]
async fn main() {
    fn get_future() -> must_future::MustBoxFuture<'static, ()> {
        async { }.boxed().into()
    }

    get_future(); // unused `must_future::MustBoxFuture` that must be used
}